/*
 * Copyright (c) 2017-present, CV4J Contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.cv4j.core.filters;

import com.cv4j.core.datamodel.ByteProcessor;
import com.cv4j.core.datamodel.ColorProcessor;
import com.cv4j.core.datamodel.ImageProcessor;

import java.util.Optional;

/**
 * 意味着二进制过滤器
 *
 * @author dev
 * @date 2021/07/22
 */
public class MeansBinaryFilter implements CommonFilter {
    /**
     * 过滤器
     *
     * @param src src
     * @return {@link ImageProcessor}
     */
    public Optional<ImageProcessor> filter(ImageProcessor src) {
        ImageProcessor newSrc = src;
        if (newSrc instanceof ColorProcessor) {
            newSrc.getImage().convert2Gray();
            newSrc = src.getImage().getProcessor();
        }
        int width = src.getWidth();
        int height = src.getHeight();
        byte[] gray = ((ByteProcessor) newSrc).getGray();

        float graySum = 0;
        int total = width * height;
        for (int i = 0; i < total; i++) {
            graySum += gray[i] & 0xff;
        }
        int means = (int) (graySum / total);

        // dithering
        int c1 = 0;
        for (int i = 0; i < total; i++) {
            c1 = ((gray[i] & 0xff) >= means) ? 255 : 0;
            gray[i] = (byte) c1;
        }
        return Optional.ofNullable(newSrc);
    }
}
